Irreplaceable
by trufflemores
Summary: SPOILERS for "Star Trek Into Darkness." Certain worldly creations cannot be replaced. For Spock, Jim Kirk is among them. Revisit to radioactive chamber scene. Ambiguous Spock/Kirk. COMPLETE.


**Disclaimer**: I do not own _Star Trek _or any of its characters. I'm simply writing this for fun, not profit.

When Spock runs, the world dissolves.

He cannot recognize the shapes that form around him; even less capable is he of interpreting and addressing them, recognizing their sentience as anything more than a periphery desire. His heartbeat feels thunderous in his chest, overriding all other needs as panic drives him.

At last, he stumbles into Engineering, out of breath and shaking. He knows even before he comes face-to-face with Montgomery Scott that the battle is lost, yet he cannot accept it, pressing onward as though the circumstances might change through sheer force of will.

When he sees the glass, all his resolve – steadily accumulated after hours of working in close contact with the singular anomaly that is James T. Kirk – crumples.

"Open it."

"I can't." Anguished eyes turn to him, and Spock can barely afford the fractional seconds it requires to give Scott his attention, despair spelled plain across his features. "The decontamination process is no' complete, you'd flood the whole compartment. The door's locked, sir." _I'm sorry._

It does nothing to assuage the building ache in his chest that sears with a physicality Spock cannot ignore, his knees collapsing underneath him as he falls gracelessly to the floor. Knees hit steel and hands reach outward, desperately needing assurance Kirk cannot give, and it is as if Spock's every atom screams against the reality, demanding a better answer, a more palatable solution.

One does not present itself. As he watches the broken body toil, the shattered spirit suffer, the ache in his soul deepens.

A small sign of life – a fractional acknowledgment of the continuing fight for existence – triggers Spock to move, tapping the glass with misplaced urgency. Gaining Kirk's attention will do nothing to help him now; worse, it will lead only to disappointment. Yet Spock needs it, and he cannot deny the urge, watching fretfully for a response.

Kirk's breath rasps in the air between them, heavy, potent.

Spock watches the single attempt he makes to sit up fully, all formality abandoned as he falls back instead, fingers tapping, tap-tap-tapping once more. Kirk opens his eyes at the sound, head tilting on a listless neck as his eyes – bloodshot and fading – seek out Spock's own in return. A flicker of a smile seems to cross them, resignation taking its place a moment later, grimly aware of their circumstances.

Spock's tenuous grasp on his own emotions slowly unravels when Kirk is forced to fall back, unable to comprehend the amount of suffering he must be experiencing. It is tremendous, unfathomable, and a world in which he needlessly suffers it is one in which Spock does not wish to live.

And yet: "How's our ship?"

Spock knows that there is a need, a pressing, primary need that cannot be ignored, and he sees the primitive necessity in Kirk's eyes, an unrepentant desire for satiation, and he knows, then, precisely how to respond.

It does not come easily. But at last, he says simply, "Out of danger."

It is a breath, a barely there affirmation that Spock might imagine, might bear direct witness to, Kirk's head lolling back as each breath rattles feebly in his chest. "You saved the crew."

Kirk's head tilts towards him, weaker now but even more resilient, somehow, a wry, painful smile crossing his lips. "You used what he wanted against him," he remarks. "That was a nice move."

"It is what you would have done," Spock replies, unmoving, as he stares at his captain, _his _captain, and the realization doesn't seem to sink in until just then, a fine sheen of tears building in his eyes.

_The truth is . . . I'm gonna miss you_.

_A puppyish, boyish smile, eyebrow arched expectantly. Spock opens his mouth to respond – to question Kirk's statement, more accurately – before closing his mouth without a word, refraining. Not to his surprise, Kirk makes an exasperated noise, somehow still appearing fond as he does so._

_Fascinating._

"And this," Kirk rasps, intruding on his monologue with seamless, unflinching accuracy as he tilts his head back to meet Spock's gaze, "this is what you would have done. It was only logical."

His voice almost breaks on those words, an unbidden, child-like fear arising long before the words are able to slip past his throat, a rugged, ragged, "_I'm scared, Spock,_" revealed the raw emotion underneath.

As boyish and young as Kirk was then, he appears even more vulnerable and ill-equipped now, failing to maintain even a semblance of invincibility.

"How do you choose not to feel?" he asks, and the same honest curiosity bubbles out of him, forces its way past all physical barriers and makes itself known.

Spock stares and rasps out a painful denial that he does not know. "Right now, I am failing."

Kirk looks at him and must see something in the raw honesty in his expression that, inexplicably, Spock could never convey in words before, their breaths mingling, one behind glass, the other, behind eternity. It does not take long for him to formulate his next inquiry, resignation lacing his tone.

"I want you to know . . . why I couldn't let you die," he begins, a forceful interjection amid the heavy, harsh tenor of his breaths. "Why I went back for you." His eyelids flutter shut and stay that way; Spock does not know where the impulse arises but he knows precisely how to respond, then, as he looks at Kirk, at the same man who, mere days before, promised them that they would be commandeering the flagship across the Galaxy on an exploratory mission of unprecedented levels, at the same person who always made ambitious plans and undertook them fearlessly, at the same human being that craved fulfillment and satisfaction and _joy _as deeply as Spock did.

"Because you are my friend," he surmises, a wordless affirmation passing between them as Kirk meets his gaze, surprise and gratitude showing there.

Words no longer exist between them, needless, needy, and Spock knows how little time remains to him, how little time remains to _them._ Without thinking, he presses his fingers against the glass, a salutatory gesture of good faith, a profound act of remote love. He watches, and he does not question Kirk's responsiveness for a moment as the other man raises his hand and, fingers curled, presses them against the glass, a finite gesture of solidarity.

They curve, ever so slightly, to match the same arch as Spock's fingers, the Vulcan symbol for peace, prosperity, honor, respect – a thousand other things that cannot be put into words.

_Live long and prosper_, he thinks, as he watches the last shuddering breath force its way out of Kirk's throat, his eyes glazing over as mortality descends, cocoons, encompasses totally.

He does not have time nor breath to say good-bye, staring instead at the hand that sinks slowly to the floor, at the eyes that pale and fade as the light – the human, the man, _Jim _– that once looked out at the world from them departing.

Spock tries to form a response, fails, and breathes out slowly, deeply, instead, staring at the space between them.

_Because you are my friend._

In spite of countless efforts to dissuade, deject, disillusion, and discomfort him, Kirk was . . . meaningful, to him. Beyond words, to him. Extraordinary, to him.

The loss – the realization of loss – would not come for hours, even as his breath rasped in his own throat, hot with rage and horror and _grief._

He howls at the sky, a single monosyllable of terrible proportions, and as he unleashes his fury upon the known universe, he avows to avenge the one irreplaceable joy it has taken from him.

* * *

**Author's Notes**: Occasionally, I revisit certain scenes in my writing due to their profundity.

This is one of them.

I hope you enjoyed. Let me know what you thought!

~truffles


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